//===--- TypeExpansionAnalysis.cpp - Type Expansion Analysis --------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

#define DEBUG_TYPE "typeexpansion-analysis"

#include "polarphp/pil/optimizer/analysis/TypeExpansionAnalysis.h"
#include "polarphp/pil/lang/PILInstruction.h"
#include "polarphp/pil/lang/PILModule.h"
#include "polarphp/pil/optimizer/utils/InstOptUtils.h"
#include "llvm/Support/Debug.h"

using namespace polar;

// The TypeExpansion Cache must not grow beyond this size.
// We limit the size of the MB cache to 2**12 because we want to limit the
// memory usage of this cache.
static const int TypeExpansionAnalysisMaxCacheSize = 4096;

const ProjectionPathList &
TypeExpansionAnalysis::getTypeExpansion(PILType B, PILModule *Mod,
                                        TypeExpansionContext context) {
   // Check whether we have the type expansion.
   auto key = std::make_pair(B, context);
   auto Iter = ExpansionCache.find(key);
   //
   if (Iter != ExpansionCache.end()) {
      return Iter->second;
   }

   // Don't expand large types. This would defeat keeping them in memory.
   if (!shouldExpand(*Mod, B)) {
      // Push the empty projection path.
      ProjectionPath P(B);
      ExpansionCache[key].push_back(P);
      return ExpansionCache[key];
   }

   // Flush the cache if the size of the cache is too large.
   if (ExpansionCache.size() > TypeExpansionAnalysisMaxCacheSize) {
      ExpansionCache.clear();
   }

   // Build the type expansion for the leaf nodes.
   ProjectionPath::expandTypeIntoLeafProjectionPaths(B, Mod, context,
                                                     ExpansionCache[key]);
   return ExpansionCache[key];
}

PILAnalysis *polar::createTypeExpansionAnalysis(PILModule *M) {
   return new TypeExpansionAnalysis(M);
}
